Field of the Background
The present invention relates to stopcocks generally, and more specifically to medical stopcocks. It also relates to fluid control devices in general and in particular to fluid control devices adapted for facilitating the aseptic administration of drugs to patients.
Description of the Background
Modern medicine requires nearly universal intravenous access and catheter usage among hospital patients. The tubing required for drug delivery must have flow rates be controlled by precise valves or stopcocks. Three-way stopcocks are known as one type of such medical instruments for fluid control. A 3-way stopcock includes three tributary tubes that are separated from one another by an angle of, for example, 90°.
The conventional 3-way stopcock is arranged between a patient and a source of infusion fluid so that when the valve body is turned, the flow of infusion fluid is selectively switched from one flow passage to another. The most common arrangement for the flows are in the shape of a “T.” In this arrangement if there is a primary input at 0° then the primary output is going to be at opposite location at 180°. The third port that acts as a tributary for flow is at 90° and can be an input or output for the flow of fluid.
It is important to note that the number of tributaries in a stopcock valve can be as low as two but also be substantially higher. There are several valves in the literature with a plurality of tributaries. The only limiting factor is the size of the tributaries or the spacing of them to allow for the valve to be selectively closed. One of the limiting factors in such cases is the cumulative size of the tributaries or the total space allocated to the valve chamber to allow for the tributaries to be selectively closed. Allowing flow to not narrow or only expand or pool is an important consideration in stopcock design.
While the tributary input and output tubes are in communication with each other for administration of a drug solution, there is a third tube, not in use, which is left unattended. Accordingly, there is a risk of microbial contamination from the end region of the tributary tube. Also, there is a concern that the drug solution, or drainage fluid, remaining within the tributary tube, which radially extends away from the main body, provides an ideal breeding ground for bacteria and other microorganisms.
Stopcocks are widely used to direct the flow of multiple compatible intravenous (IV) solutions into one IV line. A stopcock allows the user increased flexibility to select from several input lines and various combinations of the above to run into the output line or to stop the IV flow altogether. It is advantageous to run multiple lines into one line because this can dilute out a particular drug that is irritating to patients and it can also decrease the need for multiple IV sites in a patient.
While IV stopcocks are widely, used because of their advantages, they have several disadvantages. It is difficult to handle current stopcocks without touch contamination because of their small size with short connector arms that are unprotected from touch contamination. Another disadvantage of the current stopcocks is because of the short handle lengths on the rotors that are turned to select the flow desired through the stopcocks. A further disadvantage is the small internal fluid passageways that restrict the flow of viscous fluids, especially blood. This can substantially increase the time it takes to infuse these fluids Because of this, it may be necessary to utilize pumps to force the fluids through these restricted passageways. It is frequently necessary to push IV drugs through injection ports while the stopcock is in place. Therefore, lack of an injection port on commercially available stopcocks may cause inconvenience or require additional IV lines to be placed in the patient. The placement of additional lines may cause the patient discomfort and may be difficult for healthcare workers because of the patient's physiological condition. Most stopcocks are of limited input capacity and have only two input arms and one output arm. This is frequently insufficient; so multiple stopcocks are required in combination to supply sufficient input line capacity.
Small internal fluid passageway's in the current stopcock designs and subsequent restriction of the flow have other consequences. In case the stopcock is used for the viscous fluids, blood and body fluids, the stopcocks especially in their current designs, are extremely prone to get occluded by the debris and the clotted material such as blood clots.
To prevent bacterial infection from an unused tributary several stopcocks institute a continuous flow path. The primary tributary makes a “u turn” or conducts a flow pattern in the shape of a horseshoe. One problem with this “u turn” approach is that the tributary narrows to a fraction of the width at the primary entry and exit points. This can allow for clogging or a slowing of the flow.
The current level of medical stopcock technology only has a single “off position.” If the lever is not in the precise off position there may still be some flow. Conversely, if the lever is not perfectly in the on positions the flow may be constricted.
In addition to the issues of infection and valve dogging there is a lesser-mentioned design flaw in medical stopcocks. They cause skin ulcers or lesions frequently in bed-bound patients. The pointed edges of the hard plastics will cause abrasions on the skin of patients who put weight on the devices. There is a need for alternative designs that do not cause skin damage or discomfort to patients.
Additional background on medical stopcocks can be found within US Patents and the references they incorporate, numbered but not limited to: U.S. Pat. No. 8,584,701 B2, U.S. Pat. No. 8,534,321 B2, U.S. Pat. No. 8,317,758 B2, U.S. Pat. No. 7,232,428 B1, U.S. Pat. No. 5,144,972 A and U.S. Pat. No. 4,865,583 A.
The literature shows a clear need for a better designed medical stopcock.